Methods for monitoring the respiratory function of a person have many applications in medicine, sleep studies, polygraph testing, to name a few. However, such systems have involved the use of wires and electrodes or other physically invasive apparatus which contact the subject and thus interfering with their rest.
In recent years, infrared imaging technology has been applied to this problem as images in the infrared are invariant to ambient light and contain a great deal of data. The use of infrared imaging for measuring a respiratory function is based on the fact that air near the nostril has a temperature that is varying with inhale and exhale. However, problems have arisen with regards to methods for analyzing the captured infrared images or thermal video sequence such as, for instance, determining facial areas associated with respiration and then determining a respiration rate or respiration pattern from the image. Moreover, the infrared images have to be processed in real time on a frame-by-frame basis if the subject's respiratory function is intended to be continuously monitored over a prolonged period of time such as a sleep cycle.
Accordingly, what is needed in this art is a thermal imaging system and method capable of capturing a video sequence of subject(s) of interest, and processing the captured image sequence on a frame-by-frame basis such that their respiratory function can be continuously monitored in a safe, reliable, non-contact, and non-invasive manner without disturbing or disrupting the subject's rest or sleep.